Combine the chicken broth, leeks, carrots, white pepper and bay leaf in a large, heavy dutch oven or soup kettle. Bring mixture to a boil over high heat on the stove, reduce heat and allow to simmer for five minutes. Gently add the diced potatoes (don’t splash and burn yourself) and bring the soup to a boil again. Reduce heat; cover and allow soup to simmer for 15-20 min, or until potatoes are fork-tender.

While the soup bubbles, melt the butter in a large skillet, and add / sauté the sliced mushrooms, stirring often, 4-6 minutes, or until tender. Remove the bay leaf from the soup. Stir in sautéed mushrooms.

In a small bowl, combine flour, cream, and truffled parmesan rub, whisk together until smooth. Add this mixture slowly to the soup, whisking constantly to thoroughly incorporate. Bring soup back to a boil; cook and stir for 2 minutes, or until broth has thickened. If your soup is too thick add a little more stock or water to thin it back down. Adjust seasonings by adding salt and pepper to taste